Phasing arrangement for telefacsimile machines



June 24, 1941 A. GQCOOLEY 2,246,721

PHASING ARRANGEMENT FOR TELEFACSIMILE MACHINES Filed Dec. 1. 1939 &

INV EN TOR.

Patented June 24, 1941 r PHASING ARRANGEMENT FOB TELEFAC- SIMILEMACHINES Austin G. Cooley, New York, N. Y., assignor to- Wi'de WorldPhotos, Inc., New York, N. Y., a corporation of New York ApplicationDecember 1, 1939, Serial No. 307,029

UNITED STATES PATENT OFFICE as phasing." rangements are known in. thosearts, most of which require some sort of mechanical arrange-- '1 Claims.(01. ire-69.5)

' the like.

A still further feature relates to the novel organization, arrangementand relative location of parts which cooperate to generate an improvedtiming impulse for tele-facsimile scanners and other remotely controlleddevices.

Other features and advantages not specifi cally enumerated will beapparent after a comsideration of the following detaileddescriptions andthe appended claims.

In certain types of signalling devices, for example tale-facsimilescanners, telegraph distributors and the like, it is necessary not onlyto f insure that the transmitting and receiving mechanisms run in timesynchronism, but also that, spacially considered, the devices be incorrect spacial orientation with respect to each other. The procedurerequired to effect the orientation is referred to in the facsimile andtelegraph arts Various forms of phasing arment such as brushes, cams andthe like for producing a special phasing impulseat a predeterminedpointduring each revolution of the transmitting device. In accordancewith one aspect of the present invention, the phasing signal,

is produced by electro-optical means which also acts as the usualelectro-optical system for scanning the picture or other subject matterwhich is to be transmitted. Accordingly there is shown in the drawingone representative embodiment of the invention wherein,

Fig. 1 is a plan view of a tele-facslmile scanning drum and opticalsyste'm embodying the invention.

which the picture or other subject matter to be transmitted is wrappedand suitably held as disclosed for example in Patent No. 2,145,072. The

drum l is provided with a supporting shaft, 2,

which may be threaded to form a lead screw so that as the said shaftrotates, the drum I likewise rotates-and for each revolution of theshaft the drum is advanced bodily in the direction of the arrow thewidth of a scanning line. For a detailed description of a typical drumassembly that can be used, reference may be had to U. 8. Patent No.2,138,784.'"'A similar scanning drum and associated driving mechanism isprovided at the remotely located receiving point, the transmitter andreceiver drums being run in time synchronism by suitable electric motorscontrolled by synchronizing signalsas well-known in the teleiacsimileart; As is well-known in that art, it is also necessary tomaintainproper space synchronism or phasing between the drums, it beingthe usual practice to'send the phasing signals prior to the transmissionof the actual tele-facslmile signals so that once the transmitting andreceiving .drums have been phased. the tele-facsimile scanning of-thesubject matter can proceed without further adjustment. In accordancewith the present invention, the phasing signal is derivedby utilizingthe same optical system as, is used for scanning'the subject matter'tobe transmitted which subjectmatter as above pointed out, is wrappedaround drum i.

Referring to Fig. 2, there is shown in diagrammatic form associated withdrum I, a steady scanning light source 4 which by means of a suitablelens system i, illuminates the drum I in a comparatively small'spot ofintense light. It will be understood. otcourse, that the light source 4and lens system I. are enclosed in suitable lighttight housings so as toconfine the illumination of v the drum to a relatively small spot. Alsoassociated with the drum is another lens system I.

which collects the light reflected from the drum and projects it throughthe aportured mask I Fig. 2 isa schematic diagram showing an end view ofpart of the drum of Fig. 1, and the associated electro-optical systemaccording to the invention.

Fig. 3 is another view similar to Fig. 2, but

showing the drum in a different position with respect to the opticalsystem.

Referring to Fig. 1 of the drawing, there is shown a typical facsimilescanning drum I which may be of metal or other material and around andthence on to the light sensitive or photoelectric cell 8 which may be ofany well-known,

construction. It will be understood that the elements 6, I and I, areenclosed in suitable hous-v h1g3. so. that substantially the only lightwhich impin es on cell I is that which is reflected from the illuminatedspot on drum l' and which passes through the optical system 0. Ifdesired however. the system may be so arranged that a small 1 amount ofsteady leakage light may be allowed to 1 enter cell 8 independently ofdrum i if it is desired to maintain a minimum current from the cell atall times.

In order to produce a strong or pronounced phasing impulse once for eachrevolution of drum I, there is provided a split metal ring or band Iadapted to be sprung over the drum adjacent the forward end thereof. Ifdesired, the ring 9 may be fastened to the drum by screws or the like.The ring 9 is slightly smaller in internal diameter than the externaldiameter of the drum so that a small gap In is left between the ringends. Preferably, although not necessarily, the opposed ends of ring 9are slightly undercut to receive a small insert H which may be of metalhaving its exposed surface painted white, or if desired it may be apiece of white Celluloid or film preferably of the same order ofthickness as the thickness of the film carrying the subject matterwrapped around drum I. The outer surface of ring 9 is blackened in anysuitable manner.

In accordance with the invention, the lens system' 6 is designed so thatits conjugate foci are located respectively at the surface of member IIand at the aperture l2 in member 1. Furthermore, ring 9 is chosen ofsuch radial thickness that its outer peripheral surface is materiallyout of the focus of lens system 6 as shown diagrammatically in Fig. 3.

When the drum is in position to transmit a phasing impulse, member II isin optical alignment with system 6, and being white and at the focus ofthe said system, a maximum amount of light is projected through theaperture l2 on to cell 8, thus generating a large amplitude impulse orseries of impulses. This phasing signal is transmitted to the receivingequipment and is utilized to control the automatic phasing mechanismthereof in any well-known manner, preferably in accordance with thedisclosure of application Serial No. 306,465, filed November 28, 1939. t

On the other hand, when the member I l passes the optical system 6,member 9 is interposed and the illuminated spot being out of alignmentwith system 6, very little if any light is projected through theaperture I2 to cell 8. This condition is diagrammatically shown in Fig.3.

Preferably, and as described in said Patent No. 2,138,784, the drum I iscoupled to the lead screw 2 by a clutching arrangement whereby the drumcan be constantly rotated without advancing it longitudinally.Consequently, during the phasing operation, prior to actualtele-facsimile transmission, the drum merely rotates at its scanningspeed and once during every revolution a phasing impulse is transmitted.'When the phasing has been accomplished as described in said applicationSerial No. 306,465, the attendant at the receiving station operates aswitch to disconnect the phasing mechanism thereat and the transmittingand receiving machines are then in condition to be used for transmittingthe facsimile signals representing the subject matter wrapped around thedrum. During the transmission the subject matter is scanned in thewell-known manner by the same optical systemas shown in the drawing andwhich is used for the purpose of phasing, it being understood of coursethat the light-sensitive cell 8 is connected to a suitable amplifier andif de- 1 sired both the phasing impulse and the tele-facsimile signalsmay be transmitted in the form of a modulated carrier current preferablyin the audiojrequency range.

Various changes and modifications may be made herein without departingfrom the spirit and scope of the invention. Thus the relative lengths ofmembers 9 and H may be the opposite of that shown. Thus the white memberI l instead of being a small sector may extend around the major part ofthe drum, in that case member 9 will be a small sector equivalent inlength to that of member II which is shown in Figs. 1, 2 and 3. Thiswill produce a drop in signal to represent the phasing pulse.

What I claim is:

1. In combination, a rotatable scanning drum having the greater part ofits peripheral surface of uniform diameter, said drum being providedwith a peripheral blackened raised ridge havin; a substantially whitelocalized portion intermediate the ends, a light source for illuminatingsaid ridgewith a scanning light spot, a lens system focussedsubstantially at the surface of said uniform diameter portion of thedrum whereby the surface of said ridge is out of focus with said lenssystem, means to rotate said drum to bring said localized portionbetween the lens system and the light source, and a light-sensitive cellresponding to the light passing through said lens system as reflectedfrom said localized white portion.

2. In combination, a scanning drum to receive subject matter to betransmitted, an electrooptical system for scanning said subject matterto produce tele-facsimile signals including a lens system focussedsubstantially at the surface of said drum adjacent one end thereof, andmeans carried by said drum for effectively increasing the radialthickness thereof, said means having a black periphery, said means beingin alignment with said optical system and having a localized whitesection of reduced radial thickness to control the production of aphasing impulse.

3. In combination, a rotatable scanning drum, a blackened raised ringsurrounding said drum and having a substantially white gap intermediateits ends, a light source for projecting a light spot on said drum, meansto rotate said drum so that said ring is illuminated by said light spot,a lens system focussed substantially at the surface of said drum, saidring being of sufficient thickness so that when it rotates between thesaid light source and the said lens system, the light spot is out offocus of the lens system, anda lightsensitive cell energized by thelight passed through said lens system.

4. In combination, a scanning drum surrounded by a blackened raised ringhaving a gap intermediate its ends, and a light reflecting memberdisposed in said gap materially below the peripheral surface of saidring.

5. The combination according to claim 4 in which an electro-opticalsystem including a lens and a light-sensitive cell is mounted adjacentthe drum with the lens focussed on said light reflecting member andbeing materially out of focus with the outer peripheral surface of saidring.

6. The combination according to claim 4 in which said light reflectingmember is, white and thedouter reflecting surface of said ring isblackene 7. In combination, a rotatable scanning drum, anelectro-optical system for projecting a scanning spot on to said drumand for translating the reflected light from said spot into electriccurrents, and means to produce a phasing impulse comprising a blackenedring surrounding said drum and adapted to be rotated between the lightsource and lens, said ring having a light reflecting gap intermediateits ends.

AUSTIN G. COOLEY.

